Advanced prosthetic arms have been developed that communicate with a high-channel count neural interface implanted in residual peripheral nerves capable of reading multiple, independent motor signals (via recording), and providing sensory cutaneous and proprioceptive information (via stimulation), to give amputees unprecedented control over their motorized exoprostheses, particularly prostheses with high degrees of freedom.
The key technical limitation is not the development of an advanced arm itself, which largely has been accomplished, but instead includes 1) a method of attaching the arm reliably to the body; and 2) a means of communicating bidirectionally with the arm, to provide control signals and to obtain sensory information.
Socket-type attachment of an artificial limb (exoprosthesis) to the residual limb is the current standard of care, but is often inadequate. The technology often fails when applied to short residual limbs and can cause discomfort, pain, and severe soft-tissue necrosis. Consequently, alternative docking systems, Percutaneous Osseointegrated Prostheses (POPs), are being developed that typically have three basic components: (1) an endoprosthesis that attaches to and integrates with bone, (2) a subdermal barrier to infection, and (3) a load-bearing percutaneous post. Despite some successes, infection remains a serious problem, and comparable clinical devices for people with upper-limb loss have not been perfected.
Progress has been made in the development of long-term POPs that provide direct attachment to the user's skeleton and direct communication with the user's motor and sensory neurons within nerves, via a peripheral nerve interface such as the Utah Slanted Electrode Array (USEA) or other high-channel count neural interface communicating with peripheral nerves, yet further design is warranted. Advances in structural integrity, protection of the fragile wiring of peripheral nerve interfaces, resistance against infections introduced by transcutaneous breaches, and ease of assembly and implantation could be beneficial for providing amputees with desired comfort and control of motorized artificial arm.